Belt tensioning system and belt tensioner therefor

ABSTRACT

A belt tensioning system, a belt tensioner therefor and methods of making the same are provided, the belt tensioning system includes a tensioner arm pivotally mounted to a support, and a wound coiled spring having opposed ends one of which is operatively interconnected to an abutment of the support and the other of which is operatively interconnected to tile arm, the arm having a shoulder for being engaged by the one of the opposed ends of the wound coiled spring so as to permit removal of the arm and the wound coiled spring as a self-contained unit from the support when the arm is pivoted to a certain position where the shoulder of the arm engages the one end of the spring and effectively moves the one end of the wound coiled spring out of contact with the abutment of the support, the wound coiled spring includes a helical spring having the opposed ends thereof including an inner end and an outer end, the one end of the wound coiled spring includes the outer end thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation patent application of its parentpatent application, U.S. Ser. No. 252,801, filed Jun. 6, 1994, nowabandoned, which, in turn, is a divisional patent application of itsparent patent application, U.S. Ser. No. 109,792, filed Aug. 20, 1993,now U.S. Pat. No. 5,342,249, which, in turn, is a divisional patentapplication of its parent patent application, U.S. Ser. No. 947,317,filed Sep. 18, 1992, now U.S. Pat. No. 5,277,667.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a new belt tensioning system and to a new belttensioner therefor as well as to new methods of making such a new belttensioning system and such a new belt tensioner.

2. Prior Art Statement

It is known to provide a belt tensioning system comprising a supportmeans having an abutment means, an endless transmission beltconstruction carried by the support means and arranged to move in acertain path relative to the support means, an arm pivotally mounted tothe support means, a pulley rotatably carried by the arm and being inengagement with the belt construction, and a wound coiled spring havingopposed ends one of which is operatively interconnected to the abutmentmeans of the support means and the other of which is operativelyinterconnected to the arm whereby the force of the wound coiled springtends to pivot the arm in a direction that urges the pulley against thebelt construction with a force that tensions the belt construction. Forexample, see the U.S. No. 4,886,483 to Henderson,

It is also known to applicants to provide a belt tensioning systemcomprising a support means having an abutment means, an endlesstransmission belt construction carried by the support means and arrangedto move in a certain path relative to the support means, an armpivotally mounted to the support means, a pulley rotatably carried bythe arm and being in engagement with the belt construction, and a woundcoiled spring having opposed ends one of which is operativelyinterconnected to the abutment means of the support means and the otherof which is operatively interconnected to the arm whereby the force ofthe wound coiled spring tends to pivot the arm in a direction that urgesthe pulley against the belt construction with a force that tensions thebelt construction, the arm having a shoulder means for being engaged bythe one of the opposed ends of the wound coiled spring by the force ofthe wound coiled spring so as to permit removal of the arm and the woundcoiled spring as a self-contained unit from the support means when thearm is pivoted to a certain position where the shoulder means of the armengages the one end of the wound coiled spring and effectively moves theone end of the wound coiled spring out of contact with the abutmentmeans of the support means, the wound coiled spring comprising a helicalspring having the opposed ends thereof comprising an inner end and anouter end, the one end of the wound coiled spring comprising the innerend thereof. For example see the copending patent application, U.S. Ser.No. 832,297, filed Feb. 7, 1992.

SUMMARY OF THE INVENTION

It is one of the features of the invention of the aforementionedcopending patent application, U.S. Ser. No. 832,297, filed Feb. 7, 1992,to provide a new belt tensioning system wherein the belt tensionercomprises an arm and a wound coiled spring that can be carried by thearm so as to provide a self-contained unit and which when assembled tothe support means of the system provides a means to transfer one end ofthe spring to an abutment means on the support means so that that end ofthe spring will be operatively interconnected to the support means andpermit the force of the spring to provide a tensioning force on anendless transmission belt construction that is carried by the supportmeans to move in an endless path thereon.

In particular, it was found according to the teachings of that inventionthat the am of the belt tensioner can be provided with a shoulder meansagainst which the one end of the wound coiled spring can engage so as topermit the arm and spring to be a self-contained unit to be inserted inthe belt tensioning system and be removed therefrom and when assembledto the support means can transfer the engagement of that one end of thespring from the shoulder means of the arm to an abutment means on thesupport means to effectively interconnect that one end to the supportmeans whereby the force of the spring tends to pivot the arm in adirection to apply a tensioning force to a belt construction that isengaged by a pulley rotatably carried by the arm.

However, in that invention, the one end of the spring comprised an innerend of the spring whereas it is now desired to have the one end of thespring comprising the outer end of the spring because the tensioner isto mount to a support means that is illustrated in FIG. 2 of this patentapplication.

Accordingly, one embodiment of this invention comprises a belttensioning system comprising a support means having an abutment means,an endless transmission belt construction carried by the support meansand arranged to move in a certain path relative to the support means, anarm pivotally mounted to the support means, a pulley rotatably carriedby the arm and being in engagement with the belt construction, and awound coiled spring having opposed ends one of which is operativelyinterconnected to the abutment means of the support means and the otherof which is operatively interconnected to the arm whereby the force ofthe wound coiled spring tends to pivot the arm in a direction that urgesthe pulley against the belt construction with a force that tensions thebelt construction, the arm having a shoulder means for being engaged bythe one of the opposed ends of the wound coiled spring by the force ofthe wound coiled spring so as to permit removal of the arm and the woundcoiled spring as a self-contained unit from the support means when thearm is pivoted to a certain position where the shoulder means of the armengages the one end of the wound coiled spring and effectively moves theone end of the wound coiled spring out of contact with the abutmentmeans of the support means, the wound coiled spring comprising a helicalspring having the opposed ends thereof comprising an inner end and anouter end, the one end of the coiled spring comprising the outer endthereof.

Accordingly, it is an object of this invention to provide a new belttensioning system having one or more of the novel features of thisinvention as set forth above or hereinafter shown or described.

Another object of this invention is to provide a new method of makingsuch a belt tensioning system, the method of this invention having oneor more of the novel features of this invention as set forth above orhereinafter shown or described.

Another object of this invention is to provide a new belt tensioner forsuch a belt tensioning system, the belt tensioner of this inventionhaving one or more of the novel features of this invention as set forthabove or hereinafter shown or described.

Another object of this invention is to provide a new method of makingsuch a belt tensioner, the method of this invention having one or moreof the novel features of this invention as set forth above orhereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from areading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary perspective view illustrating the new belttensioning system of this invention utilizing the new belt tensioner ofthis invention.

FIG. 2 is a view similar to FIG. 1 and illustrates the support means ofthe system of FIG. 1 when the belt tensioner and belt construction areremoved therefrom.

FIG. 3 is an exploded perspective view of the various parts that formthe new belt tensioner of this invention.

FIG. 4 is an enlarged rear view of the belt tensioner of this invention.

FIG. 5 is a side view of the belt tensioner of FIG. 4 and is taken inthe direction of the arrows 5--5 of FIG. 4.

FIG. 6 is a fragmentary front view of the support means of FIG. 2.

FIG. 7 is a reduced front view illustrating how the belt tensioner ofFIG. 4 is initially assembled to the support means of FIG. 6.

FIG. 8 is a view similar to FIG. 7 and illustrates how the belttensioner of FIG. 7 is to be pivoted in order to permit the same toapply a tensioning force to a belt construction that is illustrated inphantom lines in FIG. 8.

FIG. 9 is a fragmentary cross-sectional view taken on line 9--9 of FIG.7.

FIG. 10 is a fragmentary cross-sectional view taken on line 10--10 ofFIG. 9.

FIG. 11 is a fragmentary view similar to FIG. 10 and illustrates thetensioner disposed in a tensioning position thereof.

FIG. 12 is a view similar to FIG. 11 and illustrates the tensioner ofFIG. 11 applying a tensioning force to a belt construction.

FIG. 13 is a view illustrating the arm of the tensioner in a positionfacilitating insertion and removal.

DESCRIPTION OF THE PREFERRED EMBODIMENT

While the various features of this invention are hereinafter illustratedand described as being particularly adapted to provide a belt tensionerfor operating on a belt construction adapted to move in a certain path,it is to be understood that the various features of this invention canbe utilized singly or in various combinations thereof to provide a belttensioner for other systems as desired.

Therefore, this invention is not to be limited to only the embodimentillustrated in the drawings because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

Referring now to FIG. 1, the new belt tensioning system of thisinvention is generally indicated by the reference numeral 20 andcomprises a support means 21, an endless transmission belt construction22 that is carried by the support means 21 and is arranged to move in acertain path relative to the support means 21 and a belt tensioner ofthis invention that is generally indicated by the reference numeral 23for tensioning the belt construction 22 in a manner hereinafter setforth.

The belt tensioner 23 comprises a metallic or plastic arm 24 that ispivotally mounted to the support means 21 in a manner hereinafter setforth and carrying a rotatable pulley 25 that has a belt engagingsurface 26 disposed in rolling engagement with the side 27 of the beltconstruction 22 and normally being urged in the direction of the arrow28 in FIG. 12 by the force of a wound coiled spring 29 that has one end30 thereof operatively interconnected to the support means 21 in amanner hereinafter set forth and the other end 31 thereof operativelyinterconnected to the arm 24.

The wound coiled spring 29 comprises a helically wound flat metallicwire spring means which may have the adjacent coils thereof interleavedwith an anti-friction polymeric strip 32 whereby the spring means 29functions in a manner well known in the art. For example, see theaforementioned U.S. Pat. No. 4,886,483, to Henderson whereby this U.S.patent is being incorporated into this disclosure by this referencethereto.

The tensioner 23 of this invention is adapted to be inserted into thesupport means 21 and be removed therefrom with the spring means 29 beingcarried thereby in a self-contained manner. However, the spring means 29is adapted to have the outer end 30 thereof effectively disconnectedfrom the part 69 of the arm 24 and operatively interconnected to thesupport means 21 in a manner hereinafter set forth so that the force ofthe wound coiled spring means 29 tends to pivot the arm in the directionof the arrow 28 of FIG. 12 so that the pulley 25 will be urged againstthe belt construction 22 with a force that tensions the beltconstruction 22 all in a manner and for reasons that are fully set forthin the aforementioned U.S. Pat. No. 4,886,483, to Henderson whereby onlythe details of the structure of the belt tensioning system 20 and belttensioner 23 necessary to understand the features of this invention willbe hereinafter described.

The support means 21 comprises a supporting structure 33, such as aninternal combustion engine (not shown) of a transportation vehicle orthe like (not shown), the support means 21 being a metallic or plasticcover, mounting plate or bracket that is fastened to the supportingstructure 33 in any suitable manner, such as by bolts whereby thesupport means 21 is held fixed to the supporting structure 33.

The support means 21 as illustrated in FIGS. 2 and 6 has a cylindricalhub 36 extending outwardly from a side 37 of the support means 21 and isprovided with an internally threaded opening 38 which is adapted toreceive an externally threaded end 39 of a metallic fastening member 40in a manner hereinafter set forth, the fastening member 40, as bestillustrated in FIGS. 3 and 9, having an unthreaded enlarged cylindricalshank portion 41 joined to the threaded portion 39 by a transverselydisposed flat shoulder 42 which is adapted to engage against a flatshoulder 43 on the cylindrical part 36 of the support means 21 asillustrated in FIG. 9 whereby the fastening member 40 is adapted tofasten the tensioner 23 to the support means 21 in a manner hereinafterset forth so that the fastening member 40 is fixed from movementrelative to the support means 21.

The support means 21 has an annular wall 44 that extends outwardly fromthe side 37 thereof in a concentric manner about the cylindrical hub 36and has a slot 45 formed therein and defining an abutment means 46 forhaving the end 30 of the spring 29 engaged thereagainst in the mannerillustrated in FIG. 12 to operatively interconnect the end 30 to thesupport means 21 as will be apparent hereinafter.

The wall 44 of the support means 21 has an inner arcuate surface 47adapted to be telescopically disposed with and spaced outwardly from anouter arcuate surface 48 on a cylindrical wall 49 of the arm 24 of thebelt tensioner 23 in a manner hereinafter set forth.

The support means 21 has spaced apart walls 51 and 52 extendingoutwardly from the side 37 thereof with the walls 51 and 52 respectivelydefining surfaces 53 and 54 for respectively being engageable bysurfaces 55 and 56 on a stop extension 57 of the arm 24 of the belttensioner 23.

In addition, the surfaces 53 and 55 are initial assembly alignmentmeans. The surfaces 53 and 55 are parallel such that at initial contact,the surfaces 53 and 55 meet at one end thereof as illustrated in FIG.10.

When the tensioner 23 is first mounted to the support means 21 asillustrated in FIG. 7, the fastening member 40 is threaded into theopening 38 in the cylindrical hub 36 and secured thereto. Then, when thebelt tensioning system 20 is first utilized to apply tension to the beltconstruction 22 as shown in FIG. 8, a suitable tool 58 is disposed in arectangular opening 60 in the arm 24 by an operator for rotating the arm24 in the manner illustrated by the arrow 61 in order to assemble thebelt construction 22 in the system 20 and permit the pulley 25 to applyits tensioning force when the tool 58 is removed from the opening 60 allin a manner well known in the art.

As best illustrated in FIG. 3, the wall 49 of the arm 24 has a slot 62therein that receives a tang 64 on a disc portion 65 of an anti-frictionmember 66 that is telescoped on the cylindrical wall 49 and has anarcuate flange 67 for being inserted under the first inner coil 68 ofthe spring 29 for the reasons fully set forth in the aforementionedHenderson, U.S. Pat. No. 4,886,483.

A part or member 69 forms a portion of the arm 24 when assembledthereto, the part. 69 having a pair of spaced apart posts or rods 70 and71 that are respectively adapted to be received in openings 70' and 71'of the arm 24 until a surface 69' of the part 69 abuts the arm 24 asillustrated in FIG. 1. The part 69 also has a shoulder means 72 againstwhich the outer end 30 of the spring is adapted to engage.

In this manner, when the wound coiled spring 29 is assembled to the arm24, the inner end 31 of the spring 29 is adapted to be disposed in theslot 62 of the wall 49 so as to be interconnected to the arm 24, whilethe outer end 30 is disposed against the shoulder means 72 of the part69, the spring 29 in such assembled condition still being in a woundcondition thereof so that the same has a force tending to unwind thecoils 29' thereof in a manner well known in the art so that the spring29 remains in its assembled condition by the spring force thereof.

The end 31 of the spring 29 is disposed substantially at a right anglerelative to the inner coil 68 of the spring 29 while the outer end 30 islooped as illustrated in FIGS. 10 and 11.

The spring 29 can have its inner end 31 inserted in the slot 62 of thewall 69 of the arm 24 and the outer end 30 of the spring 29 is engagedby a suitable tool (not shown) and is wound into a position beyond thelocation of the surface 72 of the part 69. The posts 70 and 71 of thepart are then disposed respectively into the openings 70' and 71' andpushed therein. The post 70 is then affixed to the arm 24 by anysuitable means, such as by bolting, brackering, staking, soldering orwelding. Thereafter the spring 29 is unwound by the tool (not shown) toengage the surface 30' of the spring against the shoulder means 72 ofthe part 69 which is now part of the arm 24.

The pulley 25 is adapted to be rotatably mounted on a cylindrical shaftmeans 73' at the end 73 of the arm 24 and fixed thereto, such as by athreaded fastening member 74 in a manner well known in the art wherebythe pulley 25 is adapted to rotate relative to the arm 24.

The arm 24 is adapted to be rotatably mounted on the cylindrical hub 36of the support means 21 as will be apparent hereinafter as a cylindricalopening 75 passes through the central hub portion or wall 49 of the arm24 and is adapted to be lined with a cylindrical bushing 77 formed ofany suitable anti-friction material, such as a polymeric material, thathas an enlarged flanged end 78 adapted to be disposed against a side 79of the arm 24 as illustrated in FIG. 9.

In this manner, the fastening member 40 is adapted to have thecylindrical portion 41 thereof disposed in an opening 80 of thecylindrical portion of the bushing 77 as illustrated in FIG. 9 and havean enlarged head 81 thereof compact biasing means, such as a wavy washer82 between the head 81 and the flange structure 78 of the bushing 77 soas to compact the same against the side 79 of the arm 24 when thethreaded portion 39 of the fastening member 40 is fully threaded intothe threaded opening 38 of the support means 21 in the mannerillustrated in FIG. 9. In this manner, the flat shoulder 42 of thefastening member 40 abuts against the flat shoulder 43 of the projection36 as illustrated in FIG. 9 whereby the fastening member 40 is held fromrotation while the arm 24 is adapted to pivot or rotate relative theretoon the bushing 77 and, thus, pivot relative to the support means 21 eventhough the force of the biasing means 82 has axially moved the arm 24 onthe fastening member 40 until the disc portion 65 of the anti-frictionmember 66 engages a facing surface means 85 of the annular wall 44 ofthe support means 21 for subsequent sliding movement thereon.

However, in order to retain the fastening member 40 in its assembledrelation with the arm 24 and spring 29 when the belt tensioner 23 isseparate from the support means 21, the cylindrical bushing 77 has araised ledge 76 which engages with the fastening member 40 in an annularslot 42' thereof in its assembled relation with the bushing 77 and thearm 24 to retain the fastening member 40 thereto. The bushing 77 hasmeans 77' at the end thereof for snap-fitting to the annular wallportion 49 of the arm 24 when completely pushed through the opening 75of the wall 49 as illustrated in FIG. 9.

Thus, it can be seen that the belt tensioner 23 of this invention can beformed of relatively few parts by the method of this invention toprovide a self-contained unit that comprises the arm 24, the pulley 25and the wound coiled spring 29 which results in a relatively inexpensivebelt tensioner through the change in the design thereof over the designof prior known belt tensioners, such as the belt tensioner set forth inthe aforementioned U.S. Pat. No. 4,866,483 to Henderson,

When it is desired to assemble the belt tensioner 23 of this invention,in the system 20 which has the support means 21 previously fastened toor to be subsequently fastened to the support structure 33 by the boltsor other means in the manner previously set forth, the belt tensioner 23is assembled thereto in the manner illustrated in FIGS. 7 and 10 wherebythe outer end 30 of the spring 29 is disposed in the slot 45 of the wall44 and the surface means 55 and 56 of the arm 24 are disposed betweenthe means surface 53 and 54 of the support means 21 while the stopsurface 55 of the extension 57 slides in spaced relation past the stopsurface 53 of the wall 51 of the support means 21. In addition, the wall49 telescopes over the wall 36 of the support means 21 and the outer end30 of the spring 29 slips over the abutment means 46 of the wall 44 ofthe support means in the manner illustrated in FIG. 10.

The fastening member 40 then has its threaded portion 39 threaded intothe threaded opening 38 of the projection 36 until the annular shoulder42 of the fastening member 40 abuts against the surface 43 of theprojection 36 in the manner illustrated in FIG. 9 so that the biasingmeans 82 is compacted between the enlarged head 81 of the fasteningmember 40 and the flange 78 of the bushing 77 so as to compact theflange 78 of the bushing 77 against the side 79 of the arm 24 andcompact the disc portion 65 of the member 66 against the facing surfacemeans 85 of the annular wall 44 of the support means 21.

In this manner, the belt tensioner 23 is fully assembled to the supportmeans 21 and can be disposed in its operative position for tensioningthe endless transmission belt construction 22 in a manner now to bedescribed.

Once it is desired to cause the belt tensioner 23 to tension the beltconstruction 22, an appropriate tool 58 is inserted in the opening 60 ofthe arm 24 and is then utilized to rotate the arm 24 in the clockwisedirection as represented by the arrow 61 in FIG. 8 to cause the outerend 30 of the spring 29 to have its side 30' be placed against theabutment 46 of the wall 44 of the support means 21 as the shoulder 72 ofthe part 69 of the rotating arm 24 moves out of engagement with thesurface 30' of the outer end 30 of the spring 29 so that the outer end30 of the spring 29 is now operatively interconnected to the supportmeans 21, such rotation of the arm 24 in the clockwise direction asillustrated in FIGS. 8 and 11 by the arrow 61 causing the inner end 31of the spring 29 to be moved in a direction to further wind up thespring 29. In this manner, when the side 27 of the belt 22 is placedagainst the surface 26 of the pulley 25 in the manner illustrated inFIGS. 1, 8 and 12, the force of the spring 29 tending to unwind thespring 29 is now applied against the side 27 of the belt construction 22as represented by the arrow 28 in FIG. 12 to tension the belt,construction 22 in a manner well known in the art. Such tensioningposition of the belt tensioner 23 has the arm 24 with its surfaces 55and 56 disposed intermediate the surfaces 53 and 54 on the support means21 as illustrated in FIG. 12.

When it is desired to remove the belt tensioner 23 from the supportmeans 21, the belt construction 22 is removed from contact with thepulley 25 and the arm 24 is permitted to move in a counter clockwisedirection until the stop surface 55 thereof engages against the stopsurface 53 of the support means 21 at which time the shoulder 72 of thepart 69 of the rotating arm 24 now comes into engagement with thesurface 30' of the outer end 30 of the spring 29 and, in effect, removesthe surface 30' of the outer end 30 of the spring 29 from the abutment46 of the support means 21 so that the outer end 30 of the spring 29 isno longer operatively interconnected to the support means 21. At thistime, the fastening member 40 can be removed from the threaded opening38 of the support means 21 and the belt tensioner 23 can be removed as aself-contained unit from the support means 21 as the spring 29 iscarried thereby.

Thus, another belt tensioner 23 of this invention can now be utilizedwith the support means 21 in the manner previously set forth should thereason for having removed the previous belt tensioner 23 be to replacethe same.

In any event, it can be seen that this invention not only provides a newbelt tensioning system and a new belt tensioner therefor, but also thisinvention provides new methods of making such a new belt tensioningsystem and such a new belt tensioner.

While the forms and methods of this invention now preferred have beenillustrated and described as required by the Patent Statute, it is to beunderstood that other forms and method steps can be utilized and stillfall within the scope of the appended claims wherein each claim setsforth what is believed to be known in each claim prior to this inventionin the portion of each claim that is disposed before the terms "theimprovement" and sets forth what is believed to be new in each claimaccording to this invention in the portion of each claim that isdisposed after the terms "the improvement" whereby it is believed thateach claim sets forth a novel, useful and unobvious invention within thepurview of the Patent Statute.

What is claimed is:
 1. In a belt tensioner for a belt tensioning systemthat comprises a support means having an abutment means and an endlesstransmission belt construction carried by said support means andarranged to move in a certain path relative to said support means, saidtensioner comprising an arm adapted to be pivotally mounted to saidsupport means, a pulley rotatably carried by said arm and being adaptedto be in engagement with said belt construction, and a wound coiledspring having opposed ends one of which is adapted to be operativelyinterconnected to said abutment means of said support means and theother of which is operatively interconnected to said arm whereby theforce of said wound coiled spring is adapted to pivot said arm in adirection that urges said pulley against said belt construction with aforce that tensions said belt construction, said arm having a shouldermeans that is engaged by said one of said opposed ends of said woundcoiled spring by the force of said wound coiled spring so as to permitinsertion and removal of said arm and said wound coiled spring as aself-contained unit to and from said support means when said arm ispivoted to a certain position where said shoulder means of said armengages said one end of said wound coiled spring and effectively holdssaid one end of said wound coiled spring out of contact with saidabutment means of said support means, said wound coiled springcomprising a helical spring having said opposed ends thereof comprisingan inner end and an outer end, said arm having an opening therethrough,a tubular bushing means having a portion thereof disposed in saidopening, and a fastening member having a portion thereof disposed insaid portion of said tubular brushing means and having a projecting endfor mounting said arm to said support means, the improvement whereinsaid portion of said fastening member and said portion of said tubularbushing means respectively have securing means cooperating together tohold said portion of said fastening member in said portion of saidtubular bushing means in assembled relation therewith.
 2. A belttensioner as set forth in claim 1 wherein said wound coiled springcomprises a substantially flat wire helical spring.
 3. A belt tensioneras set forth in claim 1 wherein said arm has surface means adapted to bedisposed for movement relative to a cylindrical hub of said supportmeans.
 4. A belt tensioner as set forth in claim 1 wherein saidfastening member is rotatably carried by said arm.
 5. A belt tensioneras set forth in claim 4 wherein said arm is rotatably disposed on saidfastening member.
 6. A belt tensioner as set forth in claim 5 whereinsaid tubular bushing means is disposed between said fastening member andsaid arm to facilitate rotational movement therebetween.
 7. A belttensioner as set forth in claim 6 wherein said tubular bushing means hasan annular flange engaging said arm, said fastening member having anenlarged head for compacting said annular flange against said arm.
 8. Abelt tensioner as set forth in claim 1 wherein said shoulder means ofsaid arm comprises a part having a pair of posts extending therefrom,said arm having a pair of openings therein respectively receiving saidposts therein.
 9. A belt tensioner as set forth in claim 1 wherein saidsecuring means of said fastening member comprises an annular groove insaid fastening member, said securing means of said tubular bushing meanscomprising an annular projection disposed in said annular groove.
 10. Abelt tensioner as set forth in claim 1 wherein said one end of saidwound coiled spring comprises said outer end thereof.